1. Field of the Invention
The present invention relates to a display device and a light-emitting device using light-emitting elements.
2. Description of the Related Art
Recently, display devices such as liquid crystal display devices, typified by, for example, a liquid crystal display television and a liquid crystal display monitor, have adopted a backlight system as a light source for emitting light from the back, side or the like of a display panel. Examples of the backlight system include what is called a side-light (or edge light) type in which a light source is disposed on two or one side of a light guide plate made of a transparent resin so that light incident on the light guide plate is reflected by a reflector disposed on the back surface of the light guide plate, thus illuminating the surface of a liquid crystal display panel.
A fluorescent tube such as a hot-cathode fluorescent tube or a cold-cathode fluorescent tube is generally used in such a backlight system.
On the other hand, technologies of backlight system using light-emitting diodes (LED), which are a type of light-emitting elements, as their light source, have been recently developed as a substitute for such backlight systems using the fluorescent tubes.
As a backlight system with a side-light type, which uses the light-emitting diodes, a backlight system is known in which a light source formed of plural light-emitting diodes mounted on a substrate is disposed on one side of a light guide plate (refer to Patent Document 1).
There has also been a proposal to mount a side surface of a board-shaped substrate of an LED chip component having plural LED chips mounted thereon to a printed wiring board for utilization as a light source for side-lighting (refer to Patent Document 2).    Patent Document 1: Japanese Patent Application Laid Open Publication No. 6-3527    Patent Document 2: Japanese Patent Application Laid Open Publication No. 10-290029
Incidentally, in backlight system with the side-light type, the length of the light source is determined according to the size of the liquid crystal display panel. In other words, a larger liquid crystal display panel requires a longer light source.
However, consider a case, for example, where a light source is formed by mounting a required number of light-emitting elements on a substrate, and by mounting the substrate, at the side surface thereof, on a printed wiring board. In this case, the influence of warpage occurring in the substrate having the light-emitting elements mounted thereto is not negligible as the length of the light source becomes longer. If the influence of the warpage is so great that it is not negligible, there is a likelihood that light emitted from the light-emitting elements mounted on the substrate may not be oriented in a desired direction, which leads to unevenness of light quantity in the display device.
An object of the present invention is to suppress occurrence of unevenness of light quantity when a light source is configured by mounting a side surface of a board-shaped substrate on a wiring board, the substrate having light-emitting elements mounted thereon.